This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-250420, filed Aug. 29, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an engine using a lubricating oil, particularly to a lubricating oil guide device therefor.
2. Description of the Related Art
In a reciprocal engine (hereinafter simply referred to as xe2x80x9cenginexe2x80x9d) in which pistons make a reciprocating motion in cylinders, journals of a crank shaft are supported rotatably at the bottom of a cylinder block so as to convert the reciprocating motions of the pistons to rotational motions.
In such an engine in which the cylinders are aligned in series, walls which extend in a direction perpendicular to the direction in which the cylinders are aligned are formed in between adjacent cylinders at the bottom of the cylinder block so as to support the journals. On the under surfaces of the walls, semicircular bearings are formed. Under the bearings, bearing caps are attached. Between these bearings and bearing caps, the journals of the crank shaft are supported rotatably.
Such an engine has an oil pump to supply an oil to portions to be lubricated such as sliding portions and a hydraulic pressure device. By means of the oil pump, the oil is supplied to the portions to be lubricated and hydraulic pressure device. The oil used in the portions to be lubricated and the hydraulic pressure device is returned to an oil pan placed at the bottom of the cylinder block.
In general, a plurality of oil flow holes are formed in the cylinder block. The lower ends of the oil flow holes are opened to the under surfaces of the walls of the cylinder block, so that the oil which passes through the oil flow holes flows through the outlets of the oil flow holes into the oil pan.
Engines have been demanded to have improved rigidity without an increase in size. Consequently, as shown in FIG. 4, the rigidity of an engine is increased by linking both ends of bearing caps B together by means of beams D. The beams D extend in the direction in which cylinders C are aligned (axial direction of a crank shaft Al). A wall F is formed between adjacent cylinders C. On the under surface of the wall F, a bearing E for supporting the upper half of a journal A rotatably is formed. From both ends of each bearing cap B, arms G extend along the wall F. The arms G are linked together by the beams D. The beams D are disposed at the bottoms of the bearing caps B away from counter weights H.
As shown in FIG. 4, a journal A is formed between a pair of adjacent counter weights H. Thus, the counter weights H rotate inside the beams D in the vicinity of the arms G. Since the counter weights H rotate within narrow spaces formed by the arms G and the beams D, negative pressure occurs in the vicinity of the arms G periodically. Due to the negative pressure, an oil I flowing through the outlets of oil flow holes J is sucked into the inside of the beams D periodically and then scattered.
As the oil I is scattered, oil drops collide with the counter weights H, thereby causing an increase in frictions of the engine. Further, as the oil I is scattered, it is liable to deteriorate by making contact with air. Further, the scatter of the oil also causes air to be mixed into the oil.
The present invention provides a lubricating oil guide device for an engine in which an oil flowing through oil flow holes of a cylinder block flows into an oil pan efficiently.
The present invention is a lubricating oil guide device for an engine comprising:
a cylinder block having a plurality of cylinders, a crank shaft which is disposed under the cylinders, and
a bearing cap module which supports the crank shaft in cooperation with the cylinder block,
wherein the bearing cap module comprises:
bearing caps which rotatably support the crank shaft in cooperation with the cylinder block,
arms which extend from both sides of the bearing caps, and
a pair of beams which extend in the axial direction of the crank shaft and link the arms together,
the cylinder block has oil flow holes which extend in a vertical direction and have oil outlets at the lower ends, and
the arm has vertical walls which sandwich an area right under the outlet and are formed along the top surface of the arm.
According to this constitution, the oil flowing through the outlets of the oil flow holes falls onto the arms, and it is guided by the vertical walls, and flows into an oil pan in the vicinity of the beam. Thus, the influence of negative pressure caused by rotations of counter weights on the oil flowing down through the outlets is suppressed.
In one embodiment of the present invention, the vertical walls extend from the inside to the outside of the rotation path of the crank shaft as viewed from the axial direction of the crank shaft. According to this constitution, the oil flowing along the arms is guided by the vertical walls from the inside to the outside of the rotation path of the crank shaft.
In one embodiment of the present invention, the vertical walls extend to the beam. According to this constitution, the oil flowing along the arms is guided to the beam by the vertical walls.
In one embodiment of the present invention, the vertical walls extend continuously from the top to bottom of the side face of the beam. According to this constitution, the oil flowing along the arms is guided to the bottom of the beam without scattering at the beam.
In one embodiment of the present invention, the arm has one end which continues to the corresponding bearing cap and the other end which is apart from the bearing cap and slopes downward from one end toward the other end, and the top portions of the vertical walls are situated at a position close to the under surface of the wall of the cylinder block where the outlet of the oil flow hole is formed so as to eliminate the space between the under surface of the wall and the arm situated right under the under surface.
In one embodiment of the present invention, the top portions of the vertical walls extend toward the under surface of the wall of the cylinder block where the outlet of the oil flow hole is formed. According to this constitution, the space between the under surface of the wall of the cylinder block and the arm is blocked, so that the scatter of the oil at the outlet of the oil flow hole is restrained.
In one embodiment of the present invention, the vertical walls are formed on only one of the pair of arms formed on each bearing cap. According to this constitution, when a blowby gas flow hole is formed above the other arm, the vertical walls do not interfere with flow of gas.
In one embodiment of the present invention, an oil pan for covering the bearing cap module is attached to the bottom of the cylinder block, and a baffle plate to be placed in the oil pan is attached to the bottom of the bearing cap module. According to this constitution, the scatter of the oil in the oil pan can be restrained by the baffle plate.
In one embodiment of the present invention, the baffle plate has through holes for guiding the oil which flows down along the top surfaces of the arms into the oil pan, in the vicinity of the lower ends of the arms. According to this constitution, the oil flowing along the top surfaces of the arms can be caused to flow into the oil pan from the vertical walls via the through holes.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.